Curtin University Homepage
  • Library
  • Help
    • Admin

    espace - Curtin’s institutional repository

    JavaScript is disabled for your browser. Some features of this site may not work without it.
    View Item 
    • espace Home
    • espace
    • Curtin Theses
    • View Item
    • espace Home
    • espace
    • Curtin Theses
    • View Item

    Convergent close-coupling approach to positron-helium collisions

    155020_Utamuratov2010.pdf (608.4Kb)
    Access Status
    Open access
    Authors
    Utamuratov, Ravshanbek
    Date
    2010
    Supervisor
    Dr. Alisher Kadyrov
    Type
    Thesis
    Award
    PhD
    
    Metadata
    Show full item record
    School
    Department of Applied Physics
    URI
    http://hdl.handle.net/20.500.11937/1603
    Collection
    • Curtin Theses
    Abstract

    This thesis presents the theoretical studies of positron scattering on the helium atom using two-center Convergent Close-Coupling (CCC) theory.The thesis organized in the following way: In the Introduction (Chapter I) the motivation for the study and the current status of the positron-helium scattering problem are presented. Other theoretical methods that previously have been applied to this problem are reviewed and their limitations are indicated. The application of the two-centre CCC to positron-helium is presented in Chapter 2. The derivations of the scattering equations and transition matrix elements are given in detail. The results of the two-centre CCC calculations for positron scattering from the helium ground state are compared with available experimental data and the results of other calculations in Chapter 3. Chapter 4 presents CCC results of positron scattering from the metastable 2[superscript]3S excited state of helium. Finally, in Chapter 5, we draw conclusions arising from this work and indicate future directions for the research.Main results of this work • The two-centre Convergent Close-Coupling method is generalized to positron scattering on the helium atom. • Cross sections, free from pseudo-resonances, are obtained for all major channels of interest and over a wide range of scattering energy. The importance of the inclusion of pseudo-states from both centers is demonstrated. • The elastic cross section below the Ps-formation threshold is obtained, for the first time, by using a two-centre close-coupling approach. • A consistent agreement of the CCC calculations with the available integrated cross section measurements of Ps-formation has been achieved at energies from the threshold of 17.8 eV up to 150 eV.• The CCC calculations exhibit a qualitative agreement with the measurements of the total cross section for ionization of the ground state of helium by positron impact. • The separation of the spin part of the total wave function is demonstrated and possible ortho- to para- Ps formation ratios are derived from first principles without assumptions. • Calculations of positron scattering from the 2[superscript]3S metastable state of helium are done for the first time. Converged results for the total scattering, Psformation, helium and Ps excitation as well as breakup cross sections are obtained. • Both considered cases (scattering from the ground and the 2[superscript]3S metastable states) confirm the equal atomic and Ps contributions to near-threshold breakup cross section, a behavior previously observed in positron scattering from hydrogen.

    Related items

    Showing items related by title, author, creator and subject.

    • Impact-parameter convergent close-coupling approach to antiproton-atom collisions
      Abdurakhmanov, Ilkhom (2011)
      This thesis is devoted to extension of the convergent close-coupling (CCC) method to heavy projectiles and its application to the theoretical studies of antiproton scattering on the hydrogen and helium targets.In the ...
    • Electron- and positron-molecule scattering: Development of the molecular convergent close-coupling method
      Zammit, M.; Fursa, Dmitry; Savage, J.; Bray, Igor (2017)
      Starting from first principles, this tutorial describes the development of the adiabatic-nuclei convergent close-coupling (CCC) method and its application to electron and (single-centre) positron scattering from diatomic ...
    • Two-centre Convergent Close-Coupling Approach to Positron and Positronium Scattering
      Rawlins, Charlie Michael (2018)
      The two-centre convergent close-coupling (CCC) approach is used to calculate antihydrogen formation cross sections via positronium scattering on antiprotons. These cross sections have been expressed in terms of simple ...
    Advanced search

    Browse

    Communities & CollectionsIssue DateAuthorTitleSubjectDocument TypeThis CollectionIssue DateAuthorTitleSubjectDocument Type

    My Account

    Admin

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Follow Curtin

    • 
    • 
    • 
    • 
    • 

    CRICOS Provider Code: 00301JABN: 99 143 842 569TEQSA: PRV12158

    Copyright | Disclaimer | Privacy statement | Accessibility

    Curtin would like to pay respect to the Aboriginal and Torres Strait Islander members of our community by acknowledging the traditional owners of the land on which the Perth campus is located, the Whadjuk people of the Nyungar Nation; and on our Kalgoorlie campus, the Wongutha people of the North-Eastern Goldfields.